Diffusion process.



J. STEWART.

DIFFUSION PROCESS.

APPLICATION FILED NOV. 26, 1909.

Patented June 28, 1910.

ANDREW a GRAHAM co PHOTO-UTHOGRAPNFRS v/AsHmcwN, D, c

has!

pa mans ra'r orrc.

JOHN STEWART, 0F LOGAN, UTAH.

DIFFUSION PROCESS.

To all whom it may concern:

Be it known that I, JOHN STEWART, a citizen of the United States,residing at Logan, in the county of Cache and State of Utah, haveinvented certain new and useful Improvements in Diffusion Processes, ofwhich the following is a specification.

This invention comprises a diffusion process for extracting sugar fromsugar beets especially, and possibly also fronrcane.

A principal object of the inventlon 1s to provide a process by which theextraction of sugar from beets may be made contlnuous.

A further object of the invention 1s to make the extraction of the sugarpractically complete, which the process now in use does not accomplish.

A further object of the invention is to enable the extraction of thesugar to be made in a much shorter space of time than the process now inuse admits of.

In the early stages of beet sugar manufacture, the beets were cut intosmall pieces and subjected to heavy pressure to obtain the sugar, thisprocess being copied from the ordinary cane sugar process. Later thechopped beets were placed in baskets and subjected to lixiviation byimmerslon in tanks of water, being lifted from one tank to another forrepeated operations. This was followed by running the water from onetank to another, instead of moving the beets, which forms the basis ofthe modern diffusion process. In this process it is attempted to takeadvantage of the fact that sugar passes through the walls of the plantcells more rapidly than some other constituents, thus giving a purerjuice than that obtained by pressure or by lixiviation, and the practicehas been to cut the beets into uniform and clear cut slices or cossettesthrough which the water was flowed to extract the sugar constituent; andin order to obtain such uniform and clear cut slices much expense hasbeen incurred, and is incurred, in beet sugar factories.

The present invention introduces, among other features, that ofdisintegrating or reducing the beets to a fine pulp, before thediffusion treatment. This enables a complete extract-ion of the sugarfrom the beets to be made in a very brief time and in a very shortdiffusion vessel, and it overcomes some of the most importantdifficulties heretofore existing with processes and apparatuses designedto operate continually.

Specification of Letters Patent. Patented June 28, 1910.

Application filed November 26, 1909.

Serial No. 530,018.

I am aware that efforts have been made to provide a continuous diffusionprocess operating upon cossettes, but they are more or lessobjectionable and complicated, in volving in some instances a repeatedpassage or flow of the liquor through the mass, in order to obtain therequired density. lVit-h the present process only one passage isnecessary, which is conducive to simple and economical operation.

An apparatus by which the invention may be performed is illustrated inthe accompanying drawing, which is a vertical sectional view of theapparatus.

Referring specifically to the drawings, I provide a cylindricaldiffusion vessel made of boiler plate or similar material, and having avertical leg 6, and an inclined leg 7 connected to the lower end of theformer, and extending upwardly therefrom at an angle of about t5. Theupper end of the inclined cylinder will extend somewhat higher than thatof the vertical cylinder, say one or two feet. The size and proportionsof the apparatus may be varied, but the diameter of the cylinders willconveniently be about three feet or more depending on the capacitydesired, and the height of the vertical cylinder will be about eight ortwelve feet. The upper end of the inclined cylinder may be slightlyconical or contracted with advantage, as indicated at 8.

These cylinders are inclosed throughout substantially their entirelength by a cylindrical steam jacket 9 which is divided into sections byannular partitions 10, and each section is provided with a steam inlet11 and an outlet 12. The cylinder 7 has a water inlet'13 at the bottom,below the vertical cylinder 6, and also a water inlet 14: at the top.

At the upper end the vertical cylinder 6 has a perforated section 15,about one foot long, through which liquid may flow from within thecylinder into the annular space 16 which is provided with an outlet pipe17 to carry the juice into the receiving vessel for the subsequenttreatment. The perfora tions in the section 15 are quite fine, toprevent escape of the disintegrated mass.

Mounted to rotate within the inclined cylinder 7 is a perforated screwconveyer 18, which extends throughout the entire length of saidcylinder. This may be mounted and driven in any suitable manner, and itis perforated for the purpose of allowing the water to flow through theconveyer blades during its passage downwardly from the top'to the bottomof the cylinder.

Located directly above the top of the vertical cylinder 6 is a shredderor disintegrating apparatus indicated at 19, and consisting preferablyof a cylinder with projections for grating, operating in connection witha concave, although other forms of graters may be substituted. Thisgrater discharges di rectly into the top of the vertical leg.

In operation the disintegrated mass from the shredder drops directlyinto the open end of the cylinder and passes downwardly in the sameuntil it reaches the screw conveyer in the inclined cylinder by which itis carried up and forced therefrom through the open upper end into anysuitable discharging device. During the same time currents of water areallowed to flow into the apparatus from the water pipes 13 and 14, thedirection of flow of the water being in an opposite direction to that inwhich the beets travel; and the sugar is diffused and extracted by thisflow of the water through the mass, the juice overflowing at the topthrough the perforated metal 15 and thence out through the dischargepipe 17 The cylinders are heated during this operation by means of steamintroduced into the jacket 9. Inasmuch as the beets are shredded intovery small particles the water has access to all parts thereof and thusmakes a very complete extraction, and also a more rapid extraction, thanwhen the mass consists of slices or cossettes.

Different temperatures are maintained in the several sections of thesteam jacket, at different stages of the process. The temperature of theexhaust pulp should be as low as practicable, say about 25 C., so as toavoid loss of heat in the waste product,

while the temperature at the end where the juice is discharged, that isthe top of the vertical cylinder, should be approximately 60 to 80 C.The intermediate portion of the apparatus should be at a temperatureintermediate these. The practically continuous steam jacket along thefull length of the cylinders is desirable for supplying the requisiteheat, but does not require the high temperature which would be necessaryif the jacket were used on merely a small part of the diffusion vessel,since there would then be a danger of locally overheating in order tomaintain the mass in the whole vessel at the desired temperature. It isexpected that the steam jacket as described will furnish suflicientheating surface on account of being supplemented by preheating the waterentering at inlet 13. Besides, with the beets in a fine state ofdivision, this process will not require the high temperature ofapproximately 80 C. now generally used in difiusion batteries, and alower temperature is in practice much to be preferred. I thus avoid thenecessity of removing the juice from the diffusing vessels and passingit through tubular heaters as is now done in all beet sugar factories,and as it is proposed to do in the process described in the SchwartzPatent No. 802331, and in other known processes, which removal of thejuice is objectionable on account of the cost-and for other reasons.

The diffusion apparatus now in use requires a greater heating surfaceand does not admit of heating the water materially before it enters theapparatus because with the slices used it is not practicable to have twoinlets for water at different temperatures and at the same time get acomplete extraction of the sugar. If with present apparatus the waterwere heated and introduced into the apparatus at the point where thepulp is discharged there would be much loss of heat, and if introducedcold the apparatus would have to be too long for practical purposes. Bymy process I avoid piping to take the juice outside of the cylinder, theprocess is simplified, and the operation and result are more uniform;and by heating the water introduced at the bottom of the ver ticalcylinder waste of heat in the discharged pulp is avoided.

The water entering through the pipe 13, at the bottom of the apparatus,is preferably heated before entering the apparatus, thus supplementingthe heating efiect provided by the jackets. The water entering the upperinlet 14 is cold, and percolates through the pulp as the pulp passes upthe inclined cylinder, thus taking up the heat contained in the pulp andat the same time extracting any remaining sugar. The perforated screwconveyer allows this flow, without the necessity for any sieves orbypasses in the inclined cylinder, which are objectionable because ofthe danger of clogging and for other reasons.

I am aware that it has been proposed to pulverize and treat the beets orcossettes after extracting nearly all the sugar and not before, but forobvious reasons this is inferior to the process described herin, sincethe latter avoids the necessity for the costly and unsatisfactoryslicing of the beets preliminary to the diffusion.

As'the result of disintegrating the beets and treating the pulp in themanner indicated it is possible to greatly shorten the time required forextracting the sugar, and it is possible to obtain a complete extractionof the sugar in a simpler and shorter diffusion battery, and alsoenables the treatment to be made continuous instead of intermittent, andalso more economical than that in any other apparatus known to me. Theapparatus described is simpler and less costly than those heretoforeproposed. Furthermore, with a fine pulp, it is unnecessary to heat themass to as high a temperature as with the coarse slices.

The apparatus may be adjusted, in order to obtain the required densityof juice without any automatic circulating devices, by varying theamount of water being delivered to the apparatus, the rate at which thebeets are delivered to the apparatus and the rate at which the screwremoves the exhausted mass; but when once adjusted to a proper workingcondition very little modification of the adjustment will be required.

What I claim is l. The diffusion process consisting in reducing thematerial to be treated to a fine pulp, passing said pulp in onedirection through an elongated chamber heated throughout substantiallyits whole length to different degrees at different places, the greatestheat being applied to the pulp at the inlet of said chamber, and flowingwater through said pulp in the opposite direction.

2. The difiusion process consisting in dis integrating the material tobe treated, passing said material through an elongated chamber in onedirection, flowing water through said material in the chamber in theopposite direction, said water being introduced at a plurality of pointsat different distances from the inlet end of the chamber, the waterintroduced nearest the said end of the chamber being at a highertemperature than that introduced elsewhere.

3. The difiusion process consisting in reducing the material to betreated to a fine pulp, passing the pulp in one direction through anelongated chamber, heating the pulp as it passes through said chamber,the

degree of heat applied decreasing toward 40 the outlet end of thechamber, and flowing water at a plurality of points into said chamberand through the pulp, the temperature of the water introduced being highest at the point nearest the inlet end of the chamber.

In testimony whereof, I aflix my signature in presence of two witnesses.

JOHN STEWART. Witnesses:

ROBERT STEWART, WALTER L. MCCLEERY.

